Regi Davis

All reassess their personal lives after witnessing a chance reunion between two long-lost lovers in the emergency room; Karev treats a troubled teen; Meredith shares her suspicions with Cristina.

Izzie continues helping to plan Derek and Meredith's wedding in spite of her cancer treatments; things don't go smoothly when Callie introduces Arizona to her father; Owen seeks out help for his post-traumatic stress disorder.

Michael is so smitten with Gob's girlfriend that he decides to let her know that Gob has been cheating on her, and Lucille tries to break up Buster and Lucille Austero.

Lilly won't let Miley pay for her class trip to Washington, and has a sale instead. She's angry when Miley pays people to buy stuff.

Michael collapses and must go to the hospital, Sucre steps on a landmine, Mahone meets up with Scylla's designer, and Trishanne has a surprising secret.

With Gideon missing and Hotch and Prentiss off the team, the BAU tackle one of their trickiest cases, a Milwaukee serial killer who uses his son as bait to ensnare women in broad daylight.